If you are looking for current updates on proposed breed bans and other canine laws in the US be sure to start with the AKC's Legislative Alerts.

The American Kennel Club (AKC) opposes breed specific legislation for these reasons:

Breed-specific laws are not the best way to protect communities. An owner intent on using his or her dogs for malicious purposes will simply be able to switch to another type of dog and continue to jeopardize public safety. The list of regulated breeds or types could grow every year without ever addressing responsible dog ownership. Deeds, not breeds, should be addressed.

Breed-specific laws are hard to enforce. Breed identification requires expert knowledge of the individual breeds, placing great burden on local officials.

Breed-specific laws are unfair to responsible owners.

Breed-specific laws increase costs for the community. Shelter costs for the community could rise as citizens abandon targeted breeds, and adoptable dogs of the targeted breeds would be euthanized at the shelter.

In some instances, breed-specific laws have been overturned on constitutional grounds. Because proper identification of what dogs would be included is difficult or impossible, the law may be deemed unconstitutionally vague. It may also be found to involve the taking of property without due process.

Strongly enforced animal control laws (such as leash laws), generic guidelines on dealing with dangerous dogs and increased public education efforts to promote responsible dog ownership are all better ways to protect communities from dangerous animals.

Since dogs must be unaltered to participate in conformation dog show and other performance events, many responsible dog owners will be forced to give up a sport that both they and their canine companions enjoy.

Breed-specific legislation is opposed by the AKC, the American Veterinary Medical Association, the National Animal Interest Alliance, National Animal Control Association, the ASPCA, and a host of national animal welfare organizations that have studied the issue and recognize that targeting breeds simply does not work.